First of all, what is the NoAI framework?
The NoAI framework provides an API to write your own AI. AIs can be written using squirrel.

What does it offer for me?
The old AI was still the same AI as in TTD which hasn't been updated for years. With this new framework several users are writing their own AIs which perform much better then the original AI, proving a better challenge to play against.

Where can I download the latest version?
NoAI is included in latest nightly.

Where can I get a new AI to play with?
You can download AIs in-game via the "Download content" button.

I want to write my own AI, where do I start?
The best starting place is the wiki. Also see AI:Introduction. The API docs are located here.

Tournament server
TrueBrain has created a tournament server and is regularly running competitions between AIs. It is currently offline. Check back in a few weeks for updates.

It is practically impossible to teach good programming to students that have had a prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration. --Edsger Dijkstra